Start a New Channel
There reaches a point where starting a second channel is actually the best option. And this happens, not just because your format changes, but because your target audience changes.
Let's say you have a cooking channel of quick and easy recipes for moms on the go. But then, you decide that you want to really get deep into the nutritional education behind the cooking. This is where you should create a different channel because not only is the format going to be different, but the target audience and the value that you are bringing that audience is different as well.